This is a known bug in those versions of the toolchain. Before sending a complaint message to our mailing list, please try to switch to our reference cross-compilation toolkit then recompile the sources. To switch to the cross-compiler just run

$ make crossgcc

Then remove the .xcompile file and retry the compilation process:

$ rm .xcompile
$ make

Flashing coreboot

You can flash the coreboot image on a flash ROM chip using either an external EEPROM-programmer or a mainboard using the flashrom user-space utility.